1. Field
Embodiments relate to a back light unit capable of uniformly guiding light generated by an LED to a light guide panel region in order to eliminate brightness fault and a liquid crystal display including the same.
2. Description of the Related Art
A liquid crystal display (LCD) displays an image by electrical or optical properties of liquid crystals. As compared to other display devices, an LCD has reduced thickness and light weight and may be operated at a low operating voltage with reduced power consumption. Therefore, LCDs are widely used for various purposes in industrial applications.
An LCD may have a liquid crystal display panel fabricated by sealing liquid crystal between two transparent sheets and applying a desired voltage thereto in order to alter directions of liquid crystal molecules which in turn varies light transmission efficiency so as to optically display an image, as well as a backlight assembly to provide light to the liquid crystal display panel.
The backlight assembly may have a light source such as a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a flat fluorescent lamp (FFL), and the like. Since such CCFLs have limitations in terms of film thickness reduction and simplification of an apparatus, improved quality of the apparatus, etc., there is a trend towards use of a light emitting diode (LED) with improved performance such as high brightness, extended lifespan and/or high color purity, as a light source. Moreover, since environmentally harmful substances such as mercury are subject to increasingly stringent regulations, use of CCFLs tends to decrease and CCFLs are gradually being replaced by LEDs, which are more environmentally friendly.
A backlight assembly using such LEDs as a light source may be classified into a direct type and a side-emitting type assembly in view of constructional features such as arrangement of the LED and shape of a light guide panel. Such direct type backlight assembly has a construction of LEDs aligned at a front side of the assembly, which makes a slim structure difficult to achieve and requires too many LEDs, causing increased production costs.
On the other hand, a side-emitting type LED backlight assembly has LEDs at both sides and leads light to a front side of the assembly via a light guide panel, so that an entire thickness of the backlight assembly is relatively decreased to attain a slim structure, as compared to the direct type assembly.
Since the side-emitting LED backlight assembly includes an LED which is a point light source to emit light at a certain radiation angle, if plural LEDs are aligned in a row, a dark spot at which emission of light is faint may exist between LEDs.
Briefly, the side-emitting type LED backlight assembly having LEDs directly aligned at lateral sides of a light guide panel as the point light source entails a hot spot problem in that light radiation angle regions and dark spot regions are repeated, causing non-uniform brightness.